Process of odorizing liquefied petroleum gases



?atenied Jan. 23, 1934 UNITED STATES PATENT OFFICE PROCESS OF ODORIZING LIQUEFIED PETROLEUM GASES Frederick E. Frey, Bartlesville, kla., assignor to Phillips Petroleum Company, Bartlesville, 0kla., a corporation of Delaware No Drawing. Application October I, 1929 Serial No. 398,109

3 Claims. (Cl. 4H)

This invention pertains to the odorizing 01' equal volatility to the liquefied gas. For example, liquefied p um as. it a soluble compound boiling at a temperature It is well known that liquefied petroleum gas somewhat higher than propane, such as disuch as butane and propane, when mixed with methylsulfide be used as an odorizer, the conair, formv explosive mixtures. As the odor of centration delivered will be less than the consuch petroleum gases is too weak to warn those centration in the liquid fuel at all times. Conpresent where such gases are escaping, the use sequently, the emptying of a cylinder by evapoof liquefied petroleum gas, as a fuel, especially ration, will cause a continuous increase in the is attended by some danger of fire and exploconcentration of the odorizer in the liquid, and

lo sion from leaks and open jets. in the gas delivered. However, I recommend I have discovered that an adequate odor may that a soluble liquid of comparatively low vapor be imparted to such gases by adding to the pressure, such as kerosene be present in the cylsame while stored in liquid condition, in a cylinder containing the mixture of propane and inder or the like, an odorous material in suflldimethylsulfide, to limit the increase in concenu cient amount to odorize a mixture 0! the gas tration that can take place when the cylinder is with the maximum amount of air that will pernearly empty, and thus prevent the discharge of mit combustion. This may be accomplishedby excessive amounts of odorous material. introducing into the cylinder containing the If a compound or limited solubility is used as liquefied gas, an odorous material of sufllcient an odorizer, I have found that some of the more so volatility to deliver the necessary concentration promising materials will evaporate too readily,

to the gas, under the high pressure developed and the concentration delivered decreased as the in the cylinder. However, very few substances propaneiuel is evaporated. I therefore propose, may be employed forthis purpose, due to the as a further example, to use with the fuel, a fact that the gas when utilized, changes from liquid oflow volatility and limited miscibility,

25 liquid to gaseous condition, and consequently, ,to dissolve a part of the odorous material to form so the proportion of the odorous substance may a separate liquid phase which will deliver a sufilvary in the gaseous fluid as the content of the cient concentration or the odorous material at cylinder diminishes, as the liquefied gas is used all stages 01' emptying by evaporation. For this from the same. purpose, glycol can be used in a cylinder of 30 In the case oi a gas consisting mainly of prcpropane iueiodorized by ammonia. s5

, pane, I have found it advisable to use an odorous It has heretofore been proposed to add odormaterial of high volatility, but the number of izing agents to a gas stream, but so far as I am substances possessing both 'the required odor aware, no proposal has been made prior to my strength and volatility is limited. Consequently, invention to incorporate an odorizing agent di- 35 special measures must be used to make materials rectly into gas while the latter is in liquid conof other than the correct volatility serve the dition and held under pressure in a cylinder or purpose. the like. The latter procedure presents prob- Furthermore, it is desirable that the concenlems which are not present in the odorizing of tration of odor delivered be fairly constant, a gas stream. For instance, it is necessary to 60 whether the cylinder is lull of liquid fuel or avoid the delivery or excessive concentration of ly mpty. a miscible odorizer from a near-empty cylinder,

In accordance with my invention, I have disand it is necessary to control the concentration covered that ii propylene is used as an odorizer throughout delivery of a charge, when an odorof propane for example, since it is highly miscible izer of limited miscibility is used in connection 45 with propane and equally volatile, it will be with liquefied gas in a cylinder. delivered in fairly constant concentration as the One prior inventor uses thio-acetone in a gas 4 contentoi the cylinderdiminishes. stream for odorizing purposes. He did not con- Therei'ore, as a part of the present invention, template the use oi organic sulfides in general, I proposes. liquefied iuel consisting essentially and dealt only with the odorizing of poisonous w 59 of propane and propylene, in which the pr'opyiuel gases, while I deal with non-poisonous gases \05 lene is present in suincient quantity to impart an which are stored in liquefied condition, and wish odor to allflammable mixtures with air. to introduce into the liquefied gas, only an I have also discovered that in odorizing liqueamount of odorizer suflicient to odorize an exfled pretroleum or the like, it is not absolutely plosive mixture (about 2.0% in air). A poison- 55 necessary to use an'odorizing substance having ous mixture 01 water or producer gas (0.05 to v glycol.

0.10% in air) would require a much higher odor concentration.

From the foregoing it will be understood that my invention involves the following:

First.The odorizing of liquefied petroleum gases to warn those present when there is a sufllcientamount of such gas escaping to form an explosive mixture with air. 7

Second..-To'impart the odorizing agent to the gas whi he latter is in liquefied condition and held'underpressure in a cylinder or the like.

Third-To employ only such agents as will furnish an odor of the necessary strength during the entire delivery of the gas from the cylinder.

Fourth.-Avoiding the delivery of excessive concentration of a miscible odorizer from a near-empty cylinder by the introduction of a suitable retaining agent such as kerosene or asaaivs odorize, and this I accomplish by the invention as explained above.

I am aware that substances other than those specifically mentioned are suitable for my purposes, and that changes may be made in the foregoing proposals, without departing iron the spirit of -the invention, as expressed in the claims.

What I claim and desire to secure by Letters Patent is:

1. A liquefied petroleum gas having admixed therewith a volatile odorizing agent in amount suflicient to odorize the leanest flammable mixture of said gas with air, and containing a substance having the characteristics of kerosene to avoid the delivery of excessive concentration of said odorizer from a substantially empty cylinder from which the gas is delivered.

2. Liquefied petroleum gas stored under pressure and having admixed therewith a.miscible odorizing agent, and a substance having the characteristics of kerosene to prevent the delivery of excessive concentration of the odorizing agent from a substantially empty chamber from which the gas is delivered.

3. Liquefied petroleum gas containing a volatile odorizing agent and'asubstance dissolving the odorizing agent, but miscible to no more than a limited degree with the liquefied petroleum gas.

FREDERICK E. F'REY. 

